﻿body{
    background-color: aliceblue;
    margin:0 auto;
    padding:20px;
    box-sizing: border-box;
    text-align: center;
}

input[type="text"]{
    width: 300px;
    padding:16px;
    font-size: 21px;
}

button{
    padding: 21px;
    background: green;
    color:#fff;
    cursor: pointer;
    font-size: 21px;
}

ul{
    list-style-type: none;
}

li{
    width: 100%;
    padding:21px;
    box-sizing: border-box;
    cursor: pointer;
}

li:hover{
    text-decoration: line-through;
    background:grey;
}